Nerve monitoring in thyroid surgery: is it worthwhile?

This study analysed the use of the commercially available Neurosign 100(R) Nerve Monitor during thyroidectomy. Consecutive patients undergoing thyroidectomy were monitored. The nerve response prior to and after thyroidectomy were compared as were the relative benefits of mono and bipolar electrodes. Twenty-one consecutive patients over 9 months were assessed. The threshold for stimulation of the recurrent laryngeal nerve was never more than 0.5 mA (range 0.2-0.5 mA) for the bipolar and 1.5 mA (range 0.2-1.5 mA) for the unipolar electrode. The threshold for the superior laryngeal nerve was 1 mA and 1.5 mA, respectively. Following resection, stimulation levels of the laryngeal nerves were unchanged. Use of the Neurosign 100 Nerve Monitor is helpful in laryngeal nerve localization and confirmation. The bipolar electrode set at 30 Hz. and 0.5 mA for the recurrent laryngeal nerve and 1.0 mA for the superior laryngeal nerve is recommended. Threshold comparison before and after resection would appear to have a prognostic value.